import java.util.LinkedList;
import java.util.Queue;

/**
 * Created with IntelliJ IDEA
 * Description:
 * User: lenovo
 * Date: 2023 -04 -19
 * Time: 8:34
 */
public class BinaryTree {

    static class TreeNode {
        public char val;
        public TreeNode left;//左孩子的引用
        public TreeNode right;//右孩子的引用

        public TreeNode(char val) {
            this.val = val;
        }
    }

    public TreeNode root;

    public TreeNode createTree() {
        TreeNode n1 = new TreeNode('A');
        TreeNode n2 = new TreeNode('B');
        TreeNode n3 = new TreeNode('C');
        TreeNode n4 = new TreeNode('D');
        TreeNode n5 = new TreeNode('E');
        TreeNode n6 = new TreeNode('F');
        TreeNode n7 = new TreeNode('G');
        TreeNode n8 = new TreeNode('H');
        n1.left = n2;
        n1.right = n3;
        n2.left = n4;
        n2.right = n5;
        n5.right = n8;
        n3.left = n6;
        n3.right = n7;
        root = n1;
        return root;
    }

    // 前序遍历DLR
    public void preOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        System.out.print(root.val + " ");
        preOrder(root.left);
        preOrder(root.right);
        return;
    }

    // 中序遍历LDR
    void inOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        inOrder(root.left);
        System.out.print(root.val + " ");
        inOrder(root.right);
        return;
    }

    // 后序遍历LRD
    void postOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.val + " ");
        return;
    }

    public int sum = 0;

    void size(TreeNode root) {
        /*//**
         * 获取节点的个数：子问题的思路
         * @param root
         * @return
         */
        if (root == null) {
            return;
        }
        size(root.left);
        size(root.right);
        sum++;
        return;
    }

    public int size2(TreeNode root) {
        if (root == null) {
            return 0;
        }
        int left = size2(root.left);
        int right = size2(root.right);
        return left + right + 1;
    }

    /*
    获取叶子节点的个数：遍历思路
    */
    public static int leafSize = 0;

    void getLeafNodeCount1(TreeNode root) {
        if (root == null) {
            return;
        }
        if (root.right == null && root.left == null) {
            leafSize++;
        }
        getLeafNodeCount1(root.left);
        getLeafNodeCount1(root.right);
    }

    /*
     获取叶子节点的个数：子问题
     */
    int getLeafNodeCount2(TreeNode root) {
        if (root == null) {
            return 0;
        }
        if (root.left == null && root.right == null) {
            return 1;
        }
        int left = getLeafNodeCount2(root.left);
        int right = getLeafNodeCount2(root.right);
        return left + right;
    }

    /*
   获取第K层节点的个数
    */
    int getKLevelNodeCount(TreeNode root, int k) {
        if (root == null) {
            return 0;
        }
        if (k == 1) {
            return 1;
        }
        int left = getKLevelNodeCount(root.left, k - 1);
        int right = getKLevelNodeCount(root.right, k - 1);
        return left + right;
    }

    /*
   获取二叉树的高度
   时间复杂度：O(N)
   */
    int getHeight(TreeNode root) {
        if (root == null) {
            return 0;
        }
        int left = getHeight(root.left);
        int right = getHeight(root.right);
        return (left > right) ? left + 1 : right + 1;
    }
    // 检测值为value的元素是否存在
    TreeNode find(TreeNode root, char val) {
        if(root==null){
            return null;
        }
        if(root.val==val){
            return root;
        }
        TreeNode left=find(root.left,val);
        TreeNode right=find(root.right,val);
        if(left==null&&right==null){
            return null;
        }
        if(left==null){
            return right;
        }
        if(right==null){
            return left;
        }
        return null;
    }
    //层序遍历(利用队列实现)
    Queue<TreeNode> queue=new LinkedList<>();
    void levelOrder(TreeNode root) {
        if(root==null){
            return;
        }
        queue.offer(root);
        while(!queue.isEmpty()){
            TreeNode tmp=queue.poll();
            System.out.print(tmp.val+" ");
            if(tmp.left!=null){
                queue.offer(tmp.left);
            }
            if(tmp.right!=null){
                queue.offer(tmp.right);
            }
        }
    }
    // 判断一棵树是不是完全二叉树
    boolean isCompleteTree(TreeNode root) {
        if(root.right==null&&root.left==null){
            return true;
        }
        if(root.left==null&&root.right!=null){
            return false;
        }
        /*if(root.right!=null&&root.left!=null){
            return true;
        }*/
        if(root.left!=null&&root.right==null){
            return true;
        }
        return isCompleteTree(root.left)&&isCompleteTree(root.right);
    }
}
